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A surprise guest gate crashed Thursday's Democratic debate: Henry Kissinger

The former foreign policy guru to President Richard Nixon took an unexpected, starring role in an exchange between Bernie Sanders and Hillary Clinton

CNN  — 

A surprise guest gate crashed Thursday’s Democratic debate: Henry Kissinger.

In a blast from the 1970s that must have left many young Democratic voters bewildered, the former foreign policy guru to President Richard Nixon took an unexpected, starring role in an exchange between Bernie Sanders and Hillary Clinton.

Kissinger won a Nobel Peace Prize for helping to arrange the end of U.S. involvement in the Vietnam War, and is credited with secret diplomacy that helped Nixon open Communist China to America and the West.

But he is reviled among many liberals over the bombing of Cambodia during the Vietnam War that led to the rise of the genocidal Khmer Rouge movement and over claims he backed a coup against a democratic government in Chile.

Sanders called on the old Cold Warrior to make the case that despite her claims to be the most qualified Democrat to serve as the next president, the more hawkish Clinton is out of tune with her party on foreign policy and national security.

“She talked about getting the approval or the support or the mentoring of Henry Kissinger,” Sanders said at the PBS Democratic presidential debate, which was simulcast on CNN. “Now, I find it rather amazing, because I happen to believe that Henry Kissinger was one of the most destructive secretaries of state in the modern history of this country,”

“I am proud to say that Henry Kissinger is not my friend. Count me in as somebody who will not be listening to Henry Kissinger,” Sanders said.

Clinton quickly turned the exchange to her advantage, replying with one of her most well-timed jabs of the night, highlighting the idea that Sanders has been reluctant to reveal who is advising him amid claims he has a threadbare national security policy.

“Well, I know journalists have asked, ‘Who you do listen to on foreign policy? And we have yet to know who that is,’” she said.

Clinton went on to say that she sought expertise as secretary of state from a raft of foreign policy experts, including Kissinger.

Delving deeper into the mists of time, Sanders recalled the foreign policy debates of the 1960s that led to the Vietnam War and spawned a tumultuous political time in which both he and Clinton came of age.

“Kissinger was one of those people during the Vietnam era who talked about the domino theory. Not everybody remembers that. You do. I do. The domino theory, you know, if Vietnam goes, China, da, da, da, da, da, da, da,” he said.

Kissinger, who is now 92, was born in Germany and fled the Nazi persecution of the Jews, coming to the United States in 1938. He became a naturalized citizen in 1943.

Kissinger served in World War II, earned his doctorate at Harvard and became a professor there. He served as national security adviser to Nixon and then as secretary of state for Nixon, continuing in that role under President Gerald Ford.

After leaving the State Department in 1977, he became a prolific globetrotting author and international consultant. His writings and advice on geopolitics remain required reading in the foreign policy community in the United States and overseas.